Field
The present invention relates to an apparatus for inspecting the curvature or the bending of the surface of a target material.
Description of Related Art
When the curvature or the bending of surfaces of plate products, such as semiconductor wafers, electronic circuit boards or steel plates, exerts a negative effect upon the performance of the products, it is required to inspect the curvature or the bending of the surfaces of such products.
In the related art, to inspect the curvature or the bending of a surface, a laser distance sensor may be used. To inspect the curvature or the bending of a surface using the laser distance sensor, laser beams are radiated onto the surface such that the laser beams reflect from the surface and are received by a measuring device. Upon receiving the reflected laser beams, the measuring device measures the distances of paths of the laser beams reflected from the surface to the measuring device. When the measured distances of the reflected laser beam paths are equal to each other, the measuring device determines that the surface of the target material is a flat surface without curvature or bending.
However, the laser distance sensor is disadvantageous in that the installation cost thereof is high and it is required to precisely control the movement of the laser distance sensor when applying the sensor over a large area. Further, when the inspection is performed using a laser distance sensor, a limited number of laser distance sensors are used, so the time required to perform the inspection is excessively long.
Korean Patent No. 0564323 discloses a technique of measuring the bending of a surface of a target material using a laser distance sensor. However, this technique cannot solve the above-mentioned problems experienced in the laser distance sensor.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.